


20 Days of Chub: Mutual Gaining

by Star_Sniper



Series: 20 Days of Chub: Eren/Armin [6]
Category: Shingeki no Kyojin | Attack on Titan
Genre: M/M, Weight Gain, fat admiration, fat!Eren, fat!Jean, fat!armin, fat!marco, modern!AU, some mild sexings
Language: English
Status: Completed
Published: 2016-11-23
Updated: 2016-11-23
Packaged: 2018-09-01 18:30:08
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,973
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8633611
Author URL: https://archiveofourown.org/users/Star_Sniper/pseuds/Star_Sniper
Summary: After graduating from Sina University, Eren, Armin, Jean and Marco decide to save money by moving in together. Marco is an up and coming chef, looking to test his skills on his housemates, and it quickly becomes obvious that he's incredibly talented when they're struggling to fit into their clothes.[20 Days of Chub taken from the 20 Days of Chub Challenge.]





	

While he could put the tightness of his trousers down to a temperamental tumble dryer shrinking his clothes, a second set of scales couldn't possibly be wrong. Armin stared down at the digital display between his feet. He stepped off the scales, watched the display flicker off, and then stepped back onto them once again. Numbers scrolled across the display, before stopping at the exact same number as they had done before. Which was more or less the same number that the first set of bathroom scales had told him. Armin inhaled sharply, his eyes transfixed on those gently glowing digits.

Twenty five pounds. How had he put on twenty five pounds in just two months?

Armin looked down at himself. A soft layer of fat coated his formerly frail frame, gathering in excess about his stomach, thighs and backside. The waistband of his pyjama bottoms had slipped underneath the swell of his belly, the faintest hint of love-handles forming at his sides. He ran his fingers down his fuller thighs, soft and supple underneath the thin fabric of his pyjama pants. A glance over his shoulder revealed that his rear was now filling out the seat of his pyjama bottoms, the material pulled tight against the striped material. 

Armin stepped back off the weighing scales, and winced on feeling himself _jiggle_. He was a certified genius, how hadn't he noticed that he was gaining weight? How had he gotten to the stage where his clothes had become tight, rather than well fitting? How had he gone from being slightly underweight, to slightly _overweight_? Armin sighed, and headed back into his and Eren's adjoining bedroom. 

“You comin' back to bed?” Eren murmured from underneath the covers, barely visible asides from several locks of dark hair, “You're up way too early for a Saturday.”

“Do you think I'm fat?” the words fell from Armin's lips before he could help himself. 

An audible sigh came from underneath the blankets. “I thought having a boyfriend meant that I'd never have to answer that question,” Eren surfaced from underneath the bed covers, blinking sleepily in the early morning light filtering in through the blinds, “Armin. You are _not_ fat.”

“But I've put on weight,” Armin argued, feeling his cheeks heat up; he hated confrontation, “Not just a couple of pounds, either.” 

“Gaining weight is just part of getting older,” Eren pointed out wearily, raking his tousled hair out of his eyes, “Armin, you've got nothing to worry about.” He threw open a corner of the bedclothes invitingly, patting at the mattress with the palm. “Come. Back. To. Bed.”

“I think that only really applies to people who are middle aged.” Armin sighed as he sat down on the edge of the bed, “Twenty five pounds in two months is a little excessive, Eren.” Sitting pushed his stomach out further than ever, a warm roll of fat that peeked out from underneath his t-shirt. Lowering his head to rest his chin down against the narrow slope of Armin's shoulder, Eren whistled lowly. 

“Wow,” Eren breathed, his warm breath tickling against Armin's neck, “You uhh.... you really have put on a bit of weight.” He slid his hand around Armin's side, his fingers pressing down against the supple fat. Armin's t-shirt hitched up as he shivered at the sensation, a not entirely unpleasant shudder going through him. Eren ran the pad of his thumb over the now fully exposed curve of Armin's belly, the lightly calloused skin catching against Armin's soft pale flesh. 

“I told you,” Armin felt himself sinking back against Eren, his skin tingling from every brush of Eren's fingers, “I _am_ getting fat.” 

“You're not fat,” Eren insisted, his fingertips skimming the warm underside of Armin's stomach, “Just a little chubby. It's cute,” he added hastily, as he felt Armin leaning forwards and away from him, “Really! If anyone can look good with a few extra pounds, then it's you.” 

Picking up his cell phone, from where it had been charging on his bedside table, Armin pulled up a Google search with a swipe of his thumb. He typed in his estimated height and his weight with a trembling finger. He wasn't entirely certain whether his stomach was churning from anxiety or anticipation as a list of websites popped up. He hit the top link, and settled back against Eren as the page loaded. Once the mass of numbers reloaded into a chart, he felt his breath catch in his throat. 

“See?” Armin held his phone up, tilting the screen to show Eren, “Google says I'm overweight.” There was something about the heavy finality of the term that made his heart race. Being told that he was underweight had always filled him with a similar feeling, the same morbid fascination that made him reassess every last detail about his body. Instead of it being how his collarbones protruded out from underneath his skin, it was the way his thighs were squashed up against one another when he was sat down. 

“Google can piss off,” Eren decided after a glance at the screen, “BMI is a load of crap anyway. Mikasa was always being told that her BMI was too high, and you just gotta look at her to know that isn't right. She's fitter than you and me put together.”

“That's because muscle weighs more than fat,” Armin lowered his phone to rest against his thigh, “Maybe the BMI system is a little outdated. But there's no denying that I've gotten bigger.” He exhaled, his stomach pushing up against Eren's palm. “I need to go on a diet. Or maybe I should join a gym.” Neither one seemed all that appealing to Armin, if he were being honest. He had a near insatiable sweet tooth, and he had never been gifted when it came to being physical. The mere idea of running sent a cold shiver down his spine. 

“I keep telling you, you look fine,” Eren covered the screen of Armin's' phone with his hand, light shining through the gaps of his fingers, “So you're a little... squishier than you used to be. So what? You _still_ look gorgeous. I meant what I said,” he tugged Armin's phone out of his slack fingers, and set it back down on his bedside table, “You really do look good with a bit of extra weight. There's something cute about seeing you with a belly,” he trailed his finger up to Armin's deeper bellybutton, “Means that you like to take care of yourself.”

Armin allowed Eren to pull him back onto the bed, guiding him so that he was led flat on his back. Eren straddled him with ease, his knees pinning down either side of Armin's softer hips. Raising his gaze to look into Eren's face, Armin felt his heart skip a beat as the last of the covers slipped from Eren's body, revealing a seemingly endless expanse of tanned skin. 

Revealing that Armin wasn't the only one to have put on a considerable amount of weight. Armin's mind raced as Eren leant down to kiss down the hollow of his throat, not noticing his own weight gain was something, but not noticing the fact that _Eren_ had gotten bigger was something he couldn't begin to comprehend. Eren's trim waist had thickened, and his toned abs had long disappeared underneath a doughy layer of fat. His arms were softer, but they still retained a somewhat firm line of muscle. Armin rolled his shoulder as Eren began kissing down his chest, his heart pounding underneath those lips. 

Of course, Armin's mind protested weakly, it was hard to tell the minute changes in someone who he saw every single day. He could recall reading a study on it once for psychology class, it was a mental state known as 'change blindness', and it was all down to how the brain perceived every day things. He spent most of his time with Eren, and his mind's image of him was the same as it had been when they had first met, at just five years old. It wasn't that Armin still pictured Eren that way, it was more that any changes Eren had gone through along the way were already a sealed deal, and so his mind didn't process it as new information. 

Armin almost lost his current train of thought as Eren's lips grazed the crest of his belly, sending a wave of pleasure through him. Eren had grown much taller since they had first met, Armin reasoned as he tangled his fingers into Eren's dark hair, but his mind wasn't constantly aware of that fact. So when Eren had started gaining weight, Armin's mind had simply filed it away as just another fact about Eren. Now, Armin gasped as Eren squeezed both sides of his belly with his strong hands, if he had spent even a short period apart from Eren, say a couple of days, _then_ he would have noticed that he had gained weight. His mind would have known to reset his image of Eren, and he would have seen that he had grown chubbier. 

Armin's heart fluttered in his throat as Eren reached his pyjama pants. Eren slipped his fingers between the straining waistband and Armin's warm flesh. He wriggled them with a teasing grin that left Armin breathless, revealing how little room there was. Eren began to roll Armin's pyjama bottoms off his hips, revealing a faint red imprint against his pale, quivering skin. Armin arched his back in assistance, his belly pushing up against Eren's own as his pyjama pants were eased over his rounder backside. Armin's eyes fell to Eren's gut, it rose and fell with his laboured breathing. A few rolls formed as Eren bent at the waist to discard Armin's pyjama pants completely, tossing them onto the floor without a second glance. Armin whipped his gaze away from Eren's stomach to his face the moment he felt those teal eyes focus on him, though given the flash of mild confusion in them, not quickly enough. 

“Kiss me?” Armin pleaded as he cupped his hands either side of Eren's face. He leant up to meet Eren's lips, masking a moan as he felt his stomach nudge back up against Eren's own. Eren sank easily into the kiss, his hands sliding down Armin's arms to graze past his sides, resting against his rounded hips. Eren deepened the kiss with a gentle swipe of his tongue against the seal of Armin's lips. Armin closed his eyes, exhilarated on feeling the weight of Eren's belly settle down against him. 

As Eren made love to him, whispering sweet nothings into the shell of his ear, Armin could appreciate the sensation of their soft bodies against one another. Eren's stomach kept pushing up against Armin's crotch, which sent a spike of hard pleasure shooting through him. Armin gasped and writhed underneath Eren's bulk, somehow everything felt more sensual with more flesh to feel it with, every touch more powerful than before. It seemed that Eren had a similar mindset, it wasn't long before he finished, followed shortly by Armin. They collapsed into a heap, both of them fighting to catch their breath. 

Armin smiled dazedly as he felt Eren kiss against the corner of his mouth. His head found Eren's soft shoulder, and he settled there, watching the tanned dome of Eren's stomach rise and fall. Eren's arm wrapped around Armin's shoulder, his fingers curling against his soft upper arm. For a moment they just laid there together, in the peaceful silence of post lovemaking. Armin felt lighter than air, despite feeling as if he had gained those twenty five pounds overnight, and he only just managed to push himself up with a trembling arm as he heard his phone buzz impatiently on the bedside table. 

**Breakfast is ready if you guys are :) - Marco**

-

Fresh from their incredibly quick shower, Eren and Armin headed downstairs, already able to smell breakfast before they had even entered the kitchen. The sight of breakfast on a weekend morning never failed to amaze Armin, it as when Marco went all out, creating every breakfast dish that he possibly could from whatever ingredients he claimed that were just 'laying around'. The truth was, Armin suspected, that Marco kept the kitchen well stocked throughout the week; not once had they ever ran out of anything. Marco had insisted on footing the food bill, in exchange for having full access to the kitchen and his housemates opinions on whatever dish he was creating at the time, which was an incredibly fair deal in Armin's opinion. 

The table was almost groaning with the sheer amount of food placed on it. A large platter of sausage and bacon was laid out in the centre, a few missing from where Jean and Marco had already helped themselves. Two piles of toast and fried bread were stacked neatly on the same plate, next to a bowl partially filled with fluffy scrambled eggs. Two small bowls of fried tomatoes and mushrooms were overshadowed by a still steaming pan of fried eggs. Three towering stacks of pancakes were being kept warm on a hot plate, and a jug of gooey maple syrup was casting amber shadows across the table surface. 

“About time you two got up.” Jean grumbled from around a mug of coffee. Armin smiled sheepishly in response, while laying a warning hand on Eren's lower arm; his boyfriend had already startled to bristle in response to Jean's accusation. He pulled Eren to sit down next to him on the opposite side of the table, making sure that he was sat opposite Jean, it was never wise to sit Jean and Eren across from one another, especially in the mornings. 

“It's the weekend,” Eren shot back quickly, “Most normal people are still in bed. Uh,” he glanced sheepishly across the table at Marco, “No offence, Marco.”

“None taken,” Marco smiled, his freckled cheeks dimpling, “I think?” 

Helping himself to a couple of pancakes, while Eren began piling sausages and rashers of bacon onto his plate, Armin found his gaze drifting to his two housemates. Marco exemplified the statement not to 'trust a skinny chef', he certainly wasn't above sampling his own food. He was almost completely round, with a plump belly that strained against the front of his shirt. His chubby cheeks were scattered with freckles, and the hint of a double chin formed whenever he smiled especially brightly. Armin smiled a little as he poured a generous amount of syrup over his pancakes, somehow Marco suited being fat, it just went hand in hand with his sunny personality. 

“Don't hog all the eggs, Jean,” Eren grabbed the bowl before Jean could take another spoonful, “You've got to be on your second helping by now! Leave some for the rest of us.” 

“If you were down here on time, maybe you'd of gotten more,” Jean challenged with a growl, stealing a sausage from underneath Eren's poised fork in retaliation, “You snooze, you lose!” He ate the sausage in just two bites, before laughing at Eren's indignant expression. 

Armin stared, a forkful of pancakes hovering halfway between his plate and his mouth, a drop of maple syrup threatening to drip back onto the plate. Marco had always been big ever sine he had met him, and according to Marco he had even been chubby as a child. It wasn't enough that he hadn't noticed his own weight gain, or Eren's, but to not notice Jean's _either_ was inexcusable. He stared at the softness of Jean's jawline, at his rounded cheeks. A subtle tilt of Armin's head revealed that a small pot belly was sticking out from the front of Jean's t-shirt, round and taut as if a dodgeball had been shoved underneath his top. 

“What?” Jean stared on catching Armin's eye. 

“Oh! Sorry. It's nothing.” Armin blushed, and stuffed his pancakes in his mouth to avoid answering further. 

As he chewed on the absolutely delicious pancake, which was rich and buttery enough to melt on his tongue, Armin tuned out Eren and Jean's argument in favour of focusing on the fact that he simply hadn't noticed that his housemates had starting gaining weight. If it was effecting all of them, he thought as swirled his next helping of pancake through a pool of syrup, it had to be something they were all doing. It wasn't as if they were eating as badly as they had in university, the only time they had ordered in fast food had been during a football game, and that had been just over a month ago. Armin swallowed a mouthful of syrup soaked pancake, and ran his tongue over his lips. 

In fact, they had been eating rather well, thanks to Marco and his cooking. He had a talent of working fruits and vegetables into his meals in a way that made them genuinely appealing, even Eren couldn't complain when a heap of butter-soaked carrots ended up on his plate. Armin sliced into another pancake with the edge of his fork, his thoughts elsewhere. Something was slowly starting to come together in his mind, and he could have kicked himself for not realising it sooner. He stared down in surprise at his rapidly emptying plate, and at the fact one tower of pancakes had gone, and he knew that none of the others had started eating any yet; their preferred method was to attack the meat and eggs first. 

Armin swallowed, and reached for his glass of milk. 

They were eating well underneath Marco's cooking. They were eating _too_ well. 

How hadn't he noticed it sooner? Armin touched the side of his swollen stomach, already piling another few pancakes onto his plate without really realising what he was doing. Marco only cooked for them in the evenings during the week, but given how hearty and large his meals were, that was more than enough. Armin rolled up half of a pancake underneath his fork, and after drizzling it in syrup, began taking bites out of it. It felt as if a veil had been lifted from his eyes, and he felt frustrated for not having noticed anything sooner. How was it that noticing his own weight gain opened his eyes to how chubby Eren and Jean had gotten?

“Amazing as always,” Jean sighed as he leant back in his chair, a hand held to the swell of his stomach, “You're gonna have to roll me out to the car if you want me to drive you into town. That's if I'll even fit behind the wheel.” He grinned as Marco leant across to kiss his cheek, and responded in kind by nuzzling the taller man's shoulder. 

“Gotta agree with him for once,” Eren admitted as he doggedly ate his way through a final sausage, his bloated stomach protruding out over the waistband of his jeans, “I'd never tell her, but you're even better than my mom. And that's saying something.” 

Lost in his thoughts, Armin leant forwards to push back his empty plate, only to gasp in surprise on feeling a dull ache of pain spread across his tender stomach. He looked down at himself, at how swollen his belly had become. His shirt had felt tight from the moment he had put it on, but now his shirt buttons were struggling to stay closed across the great curve of his stuffed stomach. Armin shifted gingerly in his chair to try and relieve some of the pressure, stifling a cry by clamping his syrup stained lips together. 

Most of the pancakes were gone, he realised dizzily, and he was fairly certain that he had eaten every last one of them. Especially given his full and throbbing stomach. 

After Eren and Jean had excused themselves, with some difficulty given how much they had eaten, Armin stayed in the kitchen to help Marco with the washing up. He stacked the plates up on the table, careful not to jostle his sore stomach, and waited for Eren and Jean to move on through to the lounge. Where, no doubt, they were going to thrash one another at video games. Armin hitched a quiet breath in between his teeth as he carried the small stack of plates to the sink, where Marco was already cheerfully elbow deep in frothy suds. Armin rubbed at his side once his hands were free, he was used to being full after eating, especially since moving in with Marco, but this was the first time he was so acutely aware of it. 

“This is a strange question,” Armin began as he took up a tea towel to begin drying the dishes Marco had already washed, “But you've noticed that we've all put on weight, right? I mean,” he looked down through his eyelashes at the plate he was drying, “I feel like I'm going mad. I knew my clothes weren't fitting as well, and then I worked out that I had put on weight this morning, but now it's like everywhere I look, people are fatter too.” He knew he was babbling, but there was something about Marco's good nature that made him easy to talk to. “I know there's 'change blindness', but I never knew it could be this extreme.”

“Armin,” Marco smiled, placing a soapy hand on his shoulder, “Slow down. Breathe for me.”

“Sorry,” Armin exhaled slowly, “It's just been a strange sort of morning for me.”

“Firstly, yes, I have noticed,” Marco smiled guiltily as he plunged his hands back into the water, “It was hard not to. Something similar happened to my family when I took over cooking. Ymir got so angry at me when she couldn't fit into her tux come prom night, she beat me over the head with Krista's corsage until all the petals fell out.” He laughed fondly at the memory, his eyes shining. “I guess that my cooking is a little fattening if you have it every day?”

“Or it's so good that we can't stop eating, even when it hurts?” Armin supplied, smiling at the mental image of Marco's older sister smacking him with a flower, though personally Ymir scared him quite a bit.

“That too,” Marco tried and failed to keep the pride out of his voice, “I can't pretend I'm not proud of that. I'm happy that my cooking is that good, you know?” he sighed wistfully, “Though I do feel bad that you're all getting fat off my cooking.”

“It's not the end of the world,” Armin was surprised at how little the extra weight bothered him, when he really thought about it, “I-I mean it's not your fault that you're so good at cooking. We're the ones stuffing our faces. I never even realised I'd put on weight, but now I look down and I wonder how I possibly couldn't notice.” His stomach was protruding out a little further than usual, due to the filling breakfast, but Armin's trousers had been nipping painfully into his side before he had even started eating. 

“'Change blindness' applies to ourselves, as well as everyone else around us,” Marco pointed out knowingly, “I mean I'd not notice if an extra freckle popped up. I don't even notice if I put on weight at this point,” he patted at his plump stomach affectionately, “So it makes sense that you wouldn't notice anything until it effected you.” 

“When I had to breathe in to do up my black jeans,” Armin murmured, quickly catching onto Marco's train of thought, “That's when I noticed. I kept thinking about it all day, blamed my jeans shrinking rather than me,” he smiled sheepishly, “-me growing. But when I got up this morning, I just had to weigh myself. Because at the back of my mind, I knew that something was going on.”

“There's your answer,” Marco nodded, a tiny roll of fat appearing briefly underneath his chin, “So when you noticed that you'd put on weight, you subconsciously started looking for it in other people. Which just so happened to be two people who were in the same situation as you.” 

Armin was grateful that he had met Marco during a psychology lecture. It had led to them becoming friends, Marco was bright and confident in contrast to Armin's awkwardness, and they had a surprising amount of things in common. Marco had been a natural at psychology, he had a gift for reading people, and analysing them without coming off a being condescending. Armin had been surprised when Marco hadn't gone on to be a therapist or a counsellor, given his innate talent for it. But, Armin noted with a wry glance at his bulging stomach, Marco was clearly talented in many areas. 

“Do you think they know?” Armin set a plate down carefully on the tiled counter top, so he could reach for another, 

“That they've put on weight?” Marco tilted his head to the side in thought, “Jean's always telling me that he's worried that he'll stuck in the doorway if he eats more of my cooking. But I don't know how much he's kidding. He's never really mentioned it to me. You know what Jean's like.” He raised an eyebrow as he squirted a line of washing up liquid across a frying pan. “And Eren?”

“I don't think he has any idea,” Armin admitted, “I asked him if I'd gotten fat earlier, he said no. But then he noticed and,” Armin hated the fact that his skin was so fair, that he blushed so easily, “- and he said it was cute. That I had nothing to worry about.” He touched his fingers to his belly in thought, it was so round and taut now. “But he's not said anything to me about himself. I don't exactly know how to bring something like that up, either.” 

A comfortable silence fell between them, punctuated by the clink of china. Armin could hear Eren and Jean in the lounge, along with the pulsating rock music of whatever game it was that they were playing. He dried the last of the plates, and moved up onto his tiptoes to pull open the overhead cupboard where they belonged. His breath caught in his throat as the pressure around his middle suddenly increased, the thin material of his shirt pulling into his sides. 

There was a soft 'pop', followed in quick succession by something clattering against the counter, and the feeling of immediate relief. Armin slowly lowered his gaze to his front, his face burning on seeing that one of his shirt buttons had popped open. An expanse of pale fat stretched underneath the gap, poking ever so slightly through it. On looking closer, Armin could see the remnants of the thread that had been left behind, and his throat grew tight.

He hadn't only popped open his button, he had managed to burst it off completely. 

“You okay?” Marco asked in concern, trying and failing to keep his eyes from the gap between Armin's shirt buttons. 

“I...” Armin trailed off. He was horrified that he had managed to pop a button off his shirt, that he had gotten fat enough to burst out of his clothes. But then was a pulse of excitement behind that dread. The same excitement he had felt when Eren had been stroking over his belly, telling him how cute he looked. He forced a sheepish laugh, and retrieved the button. “I'm okay. Really.” 

“Really?” Marco echoed, “You're sure?” 

“I'm sure,” Armin nodded, slipping the button into the pocket of his trousers, with some effort given how snug they were against his thighs, “It's complicated. I don't even know what I think about this. But I know that I don't hate it.” He lifted the stack of plates up into the cupboard, more carefully this time, and closed the door shut with a thud. “I think this is just something that I'm going to have to take as it comes. But I should probably try and lose a bit of weight.” He poked at his exposed belly with a mild frown. “I'm shorter than all of you. It shows a lot more on me.” 

“I'm with you, no matter what,” Marco wiped his hands on a tea towel, before placing them on Armin's small shoulders, “I can whip up some healthier stuff for you if you want. That's what I did for Ymir after she beat me up. Though, I'm in agreement with Eren, for the record. I think you look fine as you are.” 

“Marco,” Armin felt a rush of affectionate towards his friend, “Thank you.”

“Don't mention it,” Marco beamed in response, squeezing Armin's shoulder affectionately, “Though you don't have to start right now, do you? I've got a batch of cookies in the oven that are just waiting to be taste tested by someone who _isn't_ going to just mindlessly eat them while playing GTA,” he rolled his eyes affectionately towards the living room, “How about it?” 

“Cookies?” Armin could smell the tantalising sweet aroma wafting from the oven, his mouth watering despite how full he felt, “What kind?”

“Triple chocolate,” Marco crouched down in front of the oven, peering through the glass, “Milk chocolate mixture for the actual dough. White chocolate chips. And dark chocolate in the centre. I've been trying to be more creative lately. I just hope that I made the inner mixture gooey enough.” He pulled a face at the slowly baking contents, before pulling out his cell phone to check the timer. “Little bit longer yet.”

“I think,” Armin rubbed at the side of his stomach, a sheepish smile crossing his lips, “I think that I just might be able to manage a cookie or two. But I think that I need to go and get changed first.”

**Author's Note:**

> I'm so sorry I've not posted much lately! This has been in the works for a while.
> 
> Hopefully more time off will mean more writing in the near future <3


End file.
